Objects—pieces of paper, coins, lumps of precious metal—may serve as currency and represent specific monetary values, but what underpins the exchange of money is trust. We trust that our money will retain its value, that others will be willing to trade for it, and that it will still be in the bank when we come back for it. In recent years, cryptocurrency has emerged as a disruptive alternative to traditional money. Fundamentally, cryptocurrencies like bitcoin and ethereum function by replacing trust in banks and the government with trust in digital cryptography.

Suzana Herculano-Houzel spent most of 2003 perfecting a macabre recipe—a formula for brain soup. Sometimes she froze the jiggly tissue in liquid nitrogen, and then she liquefied it in a blender. Other times she soaked it in formaldehyde and then mashed it in detergent, yielding a smooth, pink slurry.

This model at the Museum of London depicts the first bridge over the River Thames, which was built by the Romans in the first century. Steven G. Johnson/Wikimedia Commons

This article was originally published at The Conversation and has been republished under Creative Commons.

Our knowledge about the people who lived in Roman Britain has undergone a sea change over the past decade. New research has rubbished our perception of it as a region inhabited solely by white Europeans. Roman Britain was actually a highly multicultural society that included newcomers and locals with black African ancestry and dual heritage, as well as people from the Middle East.

I’ve spent a good chunk of my life hiking the U.S. Southwest, and I’ve kicked my share of sharp rocks and prickly cactuses as I’ve walked across hot sandy stretches of desert. My hiking boots usually provide adequate protection, but I’ve endured an abundance of cuts, burns, and punctures. So I’ve often wondered: What did people do to protect their feet 1,000 years ago? And that begs another question: Did ancient people need footwear, or were their feet so tough and weathered that they could go barefoot most of the time?

Archaeologists are uncovering footprints on beaches from Canada to South Africa. The oldest human footprints, one of which is shown here, were found in Tanzania and date back over 3 million years. John Reader/Science Photo Library

This article was originally published in Hakai Magazine, an online publication about science and society in coastal ecosystems. Read more stories like this at hakaimagazine.com.

Just below the South African village of Brenton-on-Sea, there’s a beach that looks like something out of a tourism brochure: a tiny, sheltered bay with 50 meters of sandy beach at low tide, backed by 100-meter sea cliffs rising into a blue sky. Right where sand and cliffs meet, there is a low-ceilinged cave carved out of the surrounding stone by pounding waves.

The Inca Empire (1400–1532) is one of few ancient civilizations that speaks to us in multiple dimensions. Instead of words or pictograms, the Incas used khipus—knotted string devices—to communicate extraordinarily complex mathematical and narrative information. But, after more than a century of study, we remain unable to fully crack the code of the khipus. The challenge rests not in a lack of artifacts—over 1,000 khipus are known to us today—but in their variety and complexity. We confront tens of thousands of knots tied by different people, for different purposes, and in different regions of the empire. Cracking the code amounts to finding a pattern in history’s knotted haystack.